Question

Can you combine these equations and seek the angle theta that theoretically maximizes the range x, when launched at height h above the landing field?

Equations:
x=(v cos(theta)) t
-y=(v sin(theta)) t - (1/2) g (t^2)

Hint: this procedure is relatively easy on a horizontal surface, where y = 0; there the maximum range occurs when theta = 45 deg.